Both slow cookers and electric pressure cookers can produce very similar dishes but operate in entirely different ways.
Slow cookers cook in a relatively low temperature (at approximately 79°C–93°C or 175°F–200°F range) over a long period of time. Meanwhile, electric pressure cookers run at much higher temperature (over boiling point at 115°C~118°C or 239°F~244°F).
This difference in cooking mechanism results in drastically different cooking time. Typically an electric pressure cooker makes a dish under an hour, whereas the minimal cooking time for a slow cooker is 4 hours. An Electric pressure cooker saves about 75% electricity comparing to a slow cooker making a similar dish.
Apart from the difference in cooking temperature, there are two other physical differences
- Insulated housing
Slow cookers typically do not have insulated housing, whereas electric pressure cookers do. This contributes to energy efficiency advantage to electric pressure cookers.
- Sealed cooking
A electric pressure cooker is fully sealed under pressure, letting out no steams and no smells. This is not the case for slow cookers. This makes electric pressure cooker a winner in keeping the kitchen clean and the house smell free.
One disadvantage often cited against slow cookers is that vitamins and other trace nutrients are lost, particularly from vegetables, partially by enzyme action during cooking. When vegetables are cooked at higher temperatures these enzymes are rapidly denatured and have less time in which to act during cooking.
Another disadvantage of slow cookers is that they don’t heat the food at a temperature high enough to remove common toxins (for example in raw kidney beans, and some other beans). On the other hand, electric pressure cookers are very good at detoxifying food, owning to its higher than boiling point operating temperature.